1. Field of the Invention
This disclosure relates to a method of manufacturing a solar cell. In particular, this disclosure relates to a method of manufacturing a back contact solar cell.
2. Description of Related Art
Conventionally, there has been known so-called a back contact solar cell in which p-type and n-type semiconductor regions are formed on a back surface side of a solar cell (for example, following patent document 1). In this back contact solar cell, there is no need to provide an electrode on a light-receiving surface side. For this reason, this back contact solar cell can increase light receiving efficiency, and accordingly can achieve higher power generation efficiency. Also, connection of solar cells with a wiring material can be performed only on the back surface side. Hence, a wide wiring material can be used. Accordingly, a voltage drop caused by wiring multiple solar cells with a wiring material can be prevented.
In this back contact solar cell, it is necessary to form multiple kinds of semiconductor junctions on the back surface of the semiconductor substrate. Specifically, a p-type semiconductor layer and an n-type semiconductor layer needs to be formed on the back surface of the semiconductor substrate. To this end, a concerning issue is how to form the p-type semiconductor layer and the n-type semiconductor layer on the back surface of the semiconductor substrate.
For example, Patent document 1 discloses the following method as a method of manufacturing a back contact solar cell. To be more precise, first, as illustrated in FIG. 14, in-junction layer 101 being a laminate of i-type semiconductor layer 101i and n-type semiconductor layer 101n, and cover layer 102 are formed in this order on a back surface of n-type amorphous silicon substrate 100. Thereafter, portions of cover layer 102 are removed by an etching method.
Next, as illustrated in FIG. 15, cover layer 102 whose one portion is etched is used as a mask to remove portions of in-junction layer 101 by an etching method. After that, as illustrated in FIG. 16, ip-junction layer 104 being a laminate of i-type semiconductor layer 104i and p-type semiconductor layer 104p is formed. Then, cover layer 102 is removed by etching to expose portions of in-junction layer 101 covered by cover layer 102. Finally, an n-side electrode is formed on in-junction layer 101 and a p-side electrode is formed on ip-junction layer 104, so that a back contact solar cell is completed.
Patent Document: JP-A 2010-80887